Final answer:
A normal spleen is about one finger breadth in size and serves as a blood filter. Kehr's sign may indicate a ruptured spleen, which causes referred pain in the diaphragm area.
Step-by-step explanation:
The size of a normal spleen is typically about 12 cm (5 inches) long, which translates roughly to about one finger breadth.
The spleen is located just inferior to the diaphragm in the upper-left quadrant of the abdominopelvic cavity and is a vital secondary lymphoid organ.
It's important to note that the spleen is a fragile organ without a strong capsule and is often referred to as the "filter of the blood" due to its role in immune functions and blood cleaning, which includes removing dying red blood cells and microbes.
Kehr's sign is a clinical indication of a ruptured spleen, where blood spills into the area just inferior to the diaphragm, causing referred pain that corresponds to the area of the diaphragm rather than the spleen itself.